People who have domain names are generally capable of hosting websites. It's not a big burden.

If you already have a website, adding a static file or a simple 3-line handler for /.well-known/nostr.json routes is super easy too (unlike with the Lightning Address LNURL scheme which required an active process capable of generating invoices). 

 using nostr webserver+relay  but with regular DNS pointing . so how can nostr naming be an advantage? without using DNS of any sort or via onion 

 What do you mean? It's just a way to point a human-readable name to a pubkey.